EXAMINATION TABLE MOVEMENT CONTROL DEVICE, EXAMINATION TABLE MOVEMENT CONTROL METHOD, PROGRAM, AND MEDICAL IMAGE CAPTURING APPARATUS

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C § 119(a) to Japanese Patent Application No. 2024-031695 filed on Mar. 1, 2024, which is hereby expressly incorporated by reference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to an examination table movement control device, an examination table movement control method, a program, and a medical image capturing apparatus.

2. Description of the Related Art

In a medical image capturing apparatus such as an MRI apparatus, a function of recognizing a position of an examinee on an examination table and automatically moving the examination table to a scanogram imaging start position is known. For example, a camera image obtained by imaging the examinee using a camera installed on an opening surface of an opening portion of a gantry, a ceiling of an imaging room, and the like is applied to recognize the position of the examinee on the examination table. Note that MRI is an abbreviation for Magnetic Resonance Imaging.

JP2007-007255A discloses an X-ray CT apparatus that sets a scan plan based on a scanogram captured image that is registered with a camera image obtained by imaging an examinee using a video camera. Note that CT is an abbreviation for Computed Tomography.

JP2017-148110A discloses a radiation tomography system that corrects a reference irradiation condition of radiation set by assuming at least one of a required reference width or a required reference body thickness of an examinee, based on at least one of a width or a body thickness of the examinee detected by using an optical sensor.

SUMMARY OF THE INVENTION

However, for example, in a case in which a body position is head-first, with a head entering the gantry, and an imaging part is the head, in a case in which the examination table is moved by applying a movement amount of the examination table calculated based on the camera image or the like, a position of the examination table in a movement direction of the examination table may be deviated from the original target position.

Both the apparatus disclosed in JP2007-007255A and the system disclosed in JP2017-148110A have a problem in that the positional deviation of the examination table occurs, but JP2007-007255A and JP2017-148110A do not disclose the positional deviation of the examination table.

The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide an examination table movement control device, an examination table movement control method, a program, and a medical image capturing apparatus with which improvement in movement accuracy of an examination table is achieved.

A first aspect of the present disclosure provides an examination table movement control device comprising: one or more processors; and one or more memories that store a program including one or more instructions executed by the one or more processors, in which the one or more processors execute the program stored in the one or more memories to acquire, by using a sensor attached to a measurement room in which an examination table is installed, sensor-to-measurement target part distance information representing a distance from the sensor to a surface of a measurement target part of an examinee that faces the sensor in an up-down direction orthogonal to an installation surface of the examination table, the examinee being placed on a tabletop of the examination table, acquire first conversion information for converting the number of pixels in a camera image, which is generated by imaging the examinee using a camera attached to the measurement room, from a center position of the camera image to a measurement start position of the examinee into a distance from the center position of the camera image to the measurement start position, based on the sensor-to-measurement target part distance information, and convert the number of pixels in the camera image from the center position of the camera image to the measurement start position into a distance in a plane orthogonal to the up-down direction from the center position of the camera image to the measurement start position, with respect to a position in the up-down direction of the measurement start position of the examinee, by using the first conversion information.

With the examination table movement control device according to the first aspect, the number of pixels of the camera image is converted into the distance using the surface of the measurement target part of the examinee that faces the sensor as a reference. As a result, a thickness of the examinee is taken into consideration, and the movement accuracy of the examination table is improved as compared with a case in which the number of pixels of the camera image is converted into the distance using the tabletop on which the examinee is placed as a reference.

The term “acquire” is not limited to an aspect in which target information is acquired, and may include an aspect in which information serving as a basis for generating the target information is acquired and the target information is generated from the basis information.

A second aspect provides the examination table movement control device according to the first aspect, in which the one or more processors may acquire, as the first conversion information, a slope and an intercept of a linear function representing a conversion relationship between the number of pixels of the camera image and the distance for each position in the up-down direction.

According to such an aspect, the number of pixels of the camera image is converted into the distance by using the linear function representing the conversion relationship between the number of pixels of the camera image and the distance for each position in the up-down direction.

A third aspect provides the examination table movement control device according to the second aspect, in which the linear function may be derived by using a position of the tabletop in the up-down direction at a home position where the tabletop is at its lowest, home position conversion information representing the conversion relationship between the number of pixels and the distance at the home position, a position of the tabletop in the up-down direction at a highest position where the tabletop is at its highest, and highest position conversion information representing the conversion relationship between the number of pixels and the distance at the highest position.

According to such an aspect, the accuracy of the linear function representing the conversion relationship between the number of pixels of the camera image and the distance for each position in the up-down direction can be relatively improved.

A fourth aspect provides the examination table movement control device according to any one of the first to third aspects, in which the one or more processors may acquire a distance from the center position of the camera image to the measurement start position in a movement direction of the tabletop that is parallel to the plane orthogonal to the up-down direction.

In such an aspect, the moving distance of the tabletop in a plane parallel to a placement surface of the examination table is calculated.

A fifth aspect provides the examination table movement control device according to any one of the first to fourth aspects, in which the one or more processors may acquire second conversion information representing a variation in a distance from the sensor to the tabletop for each position based on the center position of the camera image in a movement direction of the tabletop, and, in a case in which the sensor is attached in an inclined state with respect to the installation surface, for the distance from the sensor to the tabletop acquired by using the sensor, correct the acquired distance from the sensor to the tabletop by using the variation at a position in the movement direction of the tabletop where the distance is derived.

According to such an aspect, in a case in which the camera is disposed to be inclined with respect to the tabletop, the moving distance of the tabletop in consideration of the inclination of the camera with respect to the tabletop is calculated.

A sixth aspect provides the examination table movement control device according to any one of the first to fifth aspects, in which the one or more processors may acquire a moving distance of the tabletop in a movement direction of the tabletop in a case in which the measurement start position of the examinee is moved to a specified position in a measurement device that measures the examinee, based on the distance from the center position of the camera image to the measurement start position of the examinee.

According to such an aspect, improvement in movement accuracy in a case in which the tabletop is moved to the specified position is achieved.

A seventh aspect provides the examination table movement control device according to the sixth aspect, in which the specified position may be a position where scanogram imaging is started.

According to such an aspect, improvement in movement accuracy in a case in which the tabletop is moved to the position where the scanogram imaging is started is achieved.

An eighth aspect provides an examination table movement control method comprising: acquiring, by using a sensor attached to a measurement room in which an examination table is installed, sensor-to-measurement target part distance information representing a distance from the sensor to a surface of a measurement target part of an examinee that faces the sensor in an up-down direction orthogonal to an installation surface of the examination table, the examinee being placed on the examination table; acquiring first conversion information for converting the number of pixels in a camera image, which is generated by imaging the examinee using a camera attached to the measurement room, from a center position of the camera image to a measurement start position of the examinee into a distance from the center position of the camera image to the measurement start position, based on the sensor-to-measurement target part distance information; and converting the number of pixels in the camera image from the center position of the camera image to the measurement start position into a distance in a plane orthogonal to the up-down direction from the center position of the camera image to the measurement start position, with respect to a position in the up-down direction of the measurement start position of the examinee, by using the first conversion information.

According to the examination table movement control method according to the eighth aspect of the present disclosure, it is possible to obtain the same effects as those of the examination table movement control device according to the first aspect. The configuration requirements of the examination table movement control device according to the second to seventh aspects can be applied as configuration requirements of the examination table movement control method according to other aspects.

A ninth aspect of the present disclosure provides a program causing a computer to implement: a function of acquiring, by using a sensor attached to a measurement room in which an examination table is installed, sensor-to-measurement target part distance information representing a distance from the sensor to a surface of a measurement target part of an examinee that faces the sensor in an up-down direction orthogonal to an installation surface of the examination table, the examinee being placed on the examination table; a function of acquiring first conversion information for converting the number of pixels in a camera image, which is generated by imaging the examinee using a camera attached to the measurement room, from a center position of the camera image to a measurement start position of the examinee into a distance from the center position of the camera image to the measurement start position, based on the sensor-to-measurement target part distance information; and a function of converting the number of pixels in the camera image from the center position of the camera image to the measurement start position into a distance in a plane orthogonal to the up-down direction from the center position of the camera image to the measurement start position, with respect to a position in the up-down direction of the measurement start position of the examinee, by using the first conversion information.

With the program according to the ninth aspect of the present disclosure, the same actions and effects as those of the examination table movement control device according to the first aspect can be obtained. The configuration requirements of the examination table movement control device according to the second to seventh aspects can be applied as configuration requirements of the program according to other aspects.

A tenth aspect provides a medical image capturing apparatus comprising: a measurement device that measures an examinee; a measurement data processing device that generates a medical image of the examinee based on a measurement result of the examinee; an examination table that is provided with a tabletop on which the examinee is placed; a sensor that is attached to a measurement room in which the examination table is installed and that acquires a distance from the sensor to an object to be measured; a camera that images the examinee placed on the tabletop to generate a camera image; and an examination table movement control device that controls an operation of the examination table, in which the examination table movement control device includes one or more processors, and one or more memories that store a program including one or more instructions executed by the one or more processors, and the one or more processors execute the program stored in the one or more memories to acquire, by using the sensor attached to the measurement room in which the examination table is installed, sensor-to-measurement target part distance information representing a distance from the sensor to a surface of a measurement target part of the examinee that faces the sensor in an up-down direction orthogonal to an installation surface of the examination table, the examinee being placed on the examination table, acquire first conversion information for converting the number of pixels in the camera image, which is generated by imaging the examinee using the camera attached to the measurement room, from a center position of the camera image to a measurement start position of the examinee into a distance from the center position of the camera image to the measurement start position, based on the sensor-to-measurement target part distance information, and convert the number of pixels in the camera image from the center position of the camera image to the measurement start position into a distance in a plane orthogonal to the up-down direction from the center position of the camera image to the measurement start position, with respect to a position in the up-down direction of the measurement start position of the examinee, by using the first conversion information.

With the medical image capturing apparatus according to the tenth aspect of the present disclosure, the same actions and effects as those of the examination table movement control device according to the first aspect can be obtained. The configuration requirements of the examination table movement control device according to the second to seventh aspects can be applied as configuration requirements of the medical image capturing apparatus according to other aspects.

According to the present disclosure, the number of pixels of the camera image is converted into the distance using the surface of the measurement target part of the examinee that faces the sensor as a reference. As a result, a thickness of the examinee is taken into consideration, and the movement accuracy of the examination table is improved as compared with a case in which the number of pixels of the camera image is converted into the distance using the tabletop on which the examinee is placed as a reference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing a configuration of an MRI apparatus.

FIG. 2 is a functional block diagram showing an electric configuration of the MRI apparatus shown in FIG. 1.

FIG. 3 is a block diagram showing a hardware configuration of an electric configuration of a console unit shown in FIG. 1.

FIG. 4 is a functional block diagram showing an electric configuration of an examination control device shown in FIG. 2.

FIG. 5 is a flowchart showing a procedure of an up-down movement calibration data generation method.

FIG. 6 is an explanatory diagram of an examination table height.

FIG. 7 is a schematic diagram of a screen on which a camera image is displayed.

FIG. 8 is a schematic diagram of another example of a screen on which a camera image is displayed.

FIG. 9 is a schematic diagram showing a specific example of a guide displayed in a superimposed manner on a camera image.

FIG. 10 is a graph showing an example of up-down movement calibration data.

FIG. 11 is an explanatory diagram of a mathematical equation representing a linear function of the graph shown in FIG. 10.

FIG. 12 is a flowchart showing a procedure of a front-rear lateral movement calibration data generation method.

FIG. 13 is an explanatory diagram of tabletop both-ends coordinate acquisition.

FIG. 14 is a graph showing an example of front-rear lateral movement calibration data.

FIG. 15 is an explanatory diagram of a mathematical equation representing a linear function of the graph shown in FIG. 14.

FIG. 16 is an explanatory diagram of an example of marking of a camera center at a home position.

FIG. 17 is an explanatory diagram of an example of marking of a camera center at a highest position of an examination table.

FIG. 18 is an explanatory diagram of acquisition of a deviation amount of tabletop center position.

FIG. 19 is an explanatory diagram of an example of marking after the tabletop is moved forward.

FIG. 20 is an explanatory diagram of an example of a difference value between a camera center and an ISO center.

FIG. 21 is a schematic diagram showing a specific example of calibration in a lateral direction and a front-rear direction.

FIG. 22 is a schematic diagram of a distance from a camera to the tabletop in a case in which the camera is inclined with respect to an installation surface.

FIG. 23 is an explanatory diagram showing an example of a measurement position on the tabletop.

FIG. 24 is a schematic diagram of calibration in a case in which the camera is inclined with respect to the installation surface.

FIG. 25 is an explanatory diagram of a scanogram imaging start position line in a case in which a head is imaged.

FIG. 26 is a schematic diagram illustrating a problem in scanogram imaging start position detection in a case of measuring the head.

FIG. 27 is a partially enlarged view of FIG. 26.

FIG. 28 is a schematic diagram illustrating a problem in scanogram imaging start position detection in a case in which an abdomen is measured.

FIG. 29 is an explanatory diagram of the scanogram imaging start position detection in a case in which the head is measured.

FIG. 30 is a schematic diagram of the scanogram imaging start position detection in a case in which the head is measured.

FIG. 31 is an explanatory diagram of a mathematical equation used for the scanogram imaging start position detection.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, the same constituent elements are denoted by the same reference numerals, and the duplicated description thereof is omitted. In addition, in the following embodiment, in a case in which a plurality of constituent elements are described and listed, it can be interpreted that at least one of the plurality of constituent elements is included.

Configuration Example of MRI Apparatus

FIG. 1 is a perspective view schematically showing a configuration of an MRI apparatus. An MRI apparatus 10 comprises a measurement device 12 including a gantry 11, an examination table 14, and a console unit 16. The measurement device 12 and the examination table 14 are disposed in an imaging room 17A, and the console unit 16 is disposed in an operating room 17B. FIG. 1 shows a state in which the examination table 14 is set at a position where a medical image is captured for an examinee. The examination table 14 is configured to be movable manually or automatically on an installation surface PP.

The examination table 14 comprises a tabletop 14A on which the examinee undergoing an image diagnosis examination is placed. The tabletop 14A is movable in each of an up-down direction, a forward direction in which the tabletop 14A enters an imaging space 11A of the gantry 11, a backward direction in which the tabletop 14A exits the imaging space 11A, and a lateral direction orthogonal to the forward direction and orthogonal to the up-down direction, by using an examination table drive unit. Hereinafter, the forward direction and the backward direction may be referred to as a front-rear direction.

The console unit 16 comprises an examination control device 20, an input device 22, and a display device 24. The examination control device 20 functions as a control device that controls a control unit of a machine room to control each device of the measurement device 12 and the examination table 14 and that executes MRI imaging for acquiring an NMR signal. In addition, the examination control device 20 functions as a device that performs processing of various types of data including processing of reconstructing an image based on the NMR signal acquired from the measurement device 12 and communication processing through a network, display of a processing result, and storage of data.

The NMR signal obtained from the measurement device 12 is subjected to signal processing and then is subjected to digital image processing, and the reconstructed image is displayed on the display device 24 of the console unit 16. Note that NMR is an English abbreviation for Nuclear Magnetic Resonance.

A camera unit 26 is installed on a ceiling of the imaging room 17A. The camera unit 26 comprises a camera and a case 26A in which the camera is accommodated. In FIG. 1, the camera is not shown. The camera is denoted by reference numeral 27 and is shown in FIG. 2.

The camera provided in the camera unit 26 images the examinee placed on the tabletop 14A and generates a camera image of the examinee. In addition, the camera provided in the camera unit 26 acquires distance information representing a distance from the camera to a subject such as the examinee.

The MRI apparatus 10 described in the embodiment is an example of a medical image capturing apparatus, and the examination control device 20 is an example of a measurement data processing device that generates a medical image of the examinee based on a measurement result of the examinee. The imaging room 17A described in the embodiment is an example of a measurement room. The camera unit 26 described in the embodiment is an example of a sensor attached to the measurement room.

Electric Configuration of MRI Apparatus

FIG. 2 is a functional block diagram showing an electric configuration of the MRI apparatus shown in FIG. 1. The measurement device 12 comprises a static magnetic field coil 32, a gradient magnetic field coil 34, and a gradient magnetic field power supply 36. The static magnetic field coil 32 generates a static magnetic field in a space in which the examinee is placed. The gradient magnetic field coil 34 provides a magnetic field gradient with respect to the static magnetic field generated by the static magnetic field coil 32. The gradient magnetic field power supply 36 is a drive power supply of the gradient magnetic field coil 34.

The measurement device 12 comprises a transmission coil 40, a receive coil 42, a transmitter 44, and a receiver 46. The transmission coil 40 generates a high-frequency magnetic field in a measurement region of the examinee. The transmitter 44 supplies a pulse current, which is an excited current, to the transmission coil 40. The receive coil 42 receives the NMR signal generated from the examinee. The receiver 46 transmits the NMR signal received by using the receive coil 42 to the examination control device 20. The NMR signal may be referred to as an echo signal.

Any one of a vertical magnetic field method or a horizontal magnetic field method is applied to the MRI apparatus 10 depending on a direction of the static magnetic field to be generated. The static magnetic field coil 32 is adopted in various forms in accordance with the above-described magnetic field method. The gradient magnetic field coil 34 comprises a plurality of coils that generate gradient magnetic fields in three axial directions orthogonal to each other. The plurality of coils provided in the gradient magnetic field coil 34 are each driven by the gradient magnetic field power supply 36. Positional information is added to the NMR signal generated from the examinee due to the application of the gradient magnetic field.

Although FIG. 2 shows an aspect in which the transmission coil 40 and the receive coil 42 are individually provided, there may be an aspect in which one coil having a function of the transmission coil 40 and a function of the receive coil 42 is provided.

The measurement device 12 comprises a sequence control device 48. The sequence control device 48 controls the operations of the gradient magnetic field power supply 36 and the transmitter 44 to control generation timings of the gradient magnetic field and the high-frequency magnetic field. The sequence control device 48 controls the operation of the receiver 46 to control a reception timing of the NMR signal and to execute the measurement. A time chart of the control applied to the sequence control device 48 is referred to as an imaging sequence, is set in advance in accordance with the measurement, and is stored in a storage device or the like provided in the examination control device 20.

The examination control device 20 controls the operation of each unit of the measurement device 12 via the sequence control device 48. In addition, the examination control device 20 functions as an operation device that executes operation processing on the NMR signal received via the receiver 46 and the sequence control device 48 and that acquires an image signal of an imaging region determined in advance. The examination control device 20 may include the sequence control device 48. The examination control device 20 may be a device constituting the MRI apparatus 10 or may be an external device independent of the MRI apparatus 10.

The examination control device 20 is electrically connected to the input device 22, the display device 24, and an external storage device 50 in a communicable manner. The display device 24 displays a result of the operation processing executed by using the examination control device 20. For example, the display device 24 displays the reconstructed image reconstructed based on the NMR signal transmitted from the measurement device 12.

A liquid crystal display, an organic EL display, a projector, or the like can be applied as the display device 24. The display device 24 may be an appropriate combination of these. The organic EL may be referred to as OEL using an abbreviation for Organic Electro-Luminescence.

The input device 22 is an interface through which the operator inputs a condition applied to the measurement, a condition applied to the operation processing, parameters, and the like. Examples of the input device 22 include a keyboard and a mouse. The display device 24 and the input device 22 may be configured as an integrated configuration using a touch panel type display. The operator may use the input device 22 to input parameters such as the number of echoes to be measured, an echo time, and an echo interval.

The camera 27 provided in the camera unit 26 generates a camera image and distance information based on depth information of the camera 27, and transmits the camera image and the distance information to the examination control device 20. For example, the camera 27 may comprise a first camera that generates a camera image and a second camera that acquires distance information.

The first camera may comprise an image sensor that converts an optical image of the subject into an electric signal. Examples of the image sensor include a CCD image sensor and a CMOS image sensor. Note that CCD is an abbreviation for Charge Coupled Device, and CMOS is an abbreviation for Complementary Metal Oxide Semiconductor.

A stereo camera can be applied as the second camera. A passive method of imaging peripheral light can be applied to the stereo camera. An active method of emitting infrared light can be applied to the stereo camera. A ToF camera method can be applied to the second camera. Note that ToF is an abbreviation for Time-of-Flight. The first camera described in the embodiment is an example of a camera that generates a camera image, and the second camera is an example of a distance measurement sensor that measures a distance to an object to be measured.

The examination control device 20 detects a position of the examinee and a posture of the examinee using the camera image. The examination control device 20 applies the detection result and the distance information of the examinee to capturing the medical image of the examinee, such as the movement control of the tabletop 14A.

For example, in a case in which a height and a lateral position of the examinee are aligned with an ISO center specified as a center of the imaging space 11A of the gantry 11, the camera image and the distance information are used. The ISO center described in the embodiment is an example of a measurement center position of a measurement device that measures the examinee.

The external storage device 50 stores data used in various types of the operation processing executed by the examination control device 20, data derived as a result of the operation processing, the conditions applied to the operation processing, the parameters applied to the operation processing, a program for executing the operation processing, and the like. The external storage device 50 may implement a part of functions of an internal storage device of the examination control device 20, or the internal storage device of the examination control device 20 may implement a part of functions of the external storage device 50.

The MRI apparatus 10 comprises an examination table drive unit 52. The examination table drive unit 52 moves the tabletop 14A in each of the up-down direction, the front-rear direction, and the lateral direction. That is, the examination table drive unit 52 comprises a drive mechanism connected to the tabletop 14A and a drive source such as a motor connected to the drive mechanism. The examination table drive unit 52 is controlled by using an examination table drive control device. The drive mechanism and the drive source are not shown. In addition, the examination table drive control device is not shown in FIG. 2. Components of the examination table drive control device are shown in FIG. 4.

Electric Configuration of Console Unit

FIG. 3 is a block diagram showing a hardware configuration of an electric configuration of a console unit shown in FIG. 1. The examination control device 20 provided in the console unit 16 is configured using a computer. The computer applied to the examination control device 20 may be a personal computer, a workstation, or a server computer.

The processing function of the examination control device 20 may be implemented by a computer system including a plurality of computers. The computer applied to the console unit 16 may be a virtual machine.

The examination control device 20 comprises a processor 82, a memory 84 as a main memory, a storage 86 as an auxiliary memory, an input/output interface 88, and a bus 90.

The processor 82 includes one or more CPUs. The processor 82 may include a GPU. In addition, the examination control device 20 may further include a processor such as a DSP, an ASIC, and a PLD. Note that GPU is an abbreviation for Graphics Processing Unit, DSP is an abbreviation for Digital Signal Processor, ASIC is an abbreviation for Application Specific Integrated Circuit, and PLD is an abbreviation for Programmable Logic Device.

The processor 82 is connected to the memory 84, the storage 86, the input/output interface 88, the input device 22, and the display device 24 via the bus 90.

The memory 84 includes a RAM. The memory 84 may include a ROM. For example, the storage 86 may include a hard disk drive or may include a solid state drive. The storage 86 may be a combination of a hard disk drive and a solid state drive. The storage 86 may include an external storage device such as a removable disk.

Note that RAM is an abbreviation for Random Access Memory, and ROM is an abbreviation for Read Only Memory. The hard disk drive may be referred to as HDD using an abbreviation for Hard Disk Drive. The solid state drive may be referred to as an SSD using an abbreviation for Solid State Drive.

The storage device including the memory 84 and the storage 86 stores programs, data, and the like for implementing various functions of the MRI apparatus 10. The processor 82 executes the program stored in the memory 84 to implement various functions of the MRI apparatus 10. The processor 82 comprehensively controls each unit of the examination control device 20, various devices and units provided in the MRI apparatus 10, and the like to perform various kinds of processing.

The input/output interface 88 includes a communication interface that is connectable to a network, a connection interface that is connectable to an external device, and the like. As the input/output interface 88 that is connectable to the external device, for example, a universal serial bus or HDMI (registered trademark) can be applied. The universal serial bus may be referred to as USB using an abbreviation for Universal Serial Bus. HDMI is an abbreviation for High-Definition Multimedia Interface.

The processor 82 communicates with various devices of the MRI apparatus 10 via the input/output interface 88, thereby transmitting and receiving necessary information.

Various instructions and information input by the operator via the input device 22 are input to the examination control device 20. The operator interactively operates the MRI apparatus 10 by using the input device 22 and the display device 24.

The display device 24 displays various kinds of information in addition to the examination image captured by the MRI apparatus 10. The display device 24 is used as a part of a user interface in a case of receiving input from the input device 22. The present disclosure is not limited to one display device 24, and a form of a multi-display comprising a plurality of display devices can be used.

The hardware configuration of the electric configuration of the console unit 16 shown in FIG. 3 is various control devices provided in the console unit 16, and can be applied to various control devices to which a computer is applied.

The processor 82 described in the embodiment is an example of one or more processors that execute a program stored in one or more memories. In addition, the memory 84 described in the embodiment is an example of one or more memories that store a program including one or more instructions executed by the one or more processors.

Electric Configuration of Examination Control Device

FIG. 4 is a functional block diagram showing an electric configuration of an examination control device shown in FIG. 2. The examination control device 20 comprises a measurement condition setting unit 100, a measurement control signal generation unit 102, and a measurement control signal output unit 104, as components related to the control of the measurement device 12 shown in FIG. 1. In addition, the examination control device 20 comprises a measurement data acquisition unit 106 and a measurement data processing unit 108 related to processing of the measurement result of the measurement device 12.

The measurement condition setting unit 100 sets a measurement condition to be applied to the sequence control device 48 shown in FIG. 2 based on an imaging protocol. Examples of the measurement condition include examinee identification information and an imaging part.

The measurement control signal generation unit 102 generates a measurement control signal to be applied to the sequence control device 48 based on the measurement condition. The measurement control signal output unit 104 transmits the measurement control signal generated by the measurement control signal generation unit 102 to the sequence control device 48. The sequence control device 48 controls the measurement of the examinee based on a specified imaging protocol.

The measurement data acquisition unit 106 acquires an NMR signal as measurement data of the examinee transmitted from the measurement device 12. The measurement data processing unit 108 generates a reconstructed image of the examinee using the acquired NMR signal of the examinee.

The examination control device 20 comprises a display signal generation unit 110. The display signal generation unit 110 generates a display signal representing information to be displayed on the display device 24 and transmits the display signal to the display device 24. For example, the display signal generation unit 110 generates a display signal representing the reconstructed image of the examinee generated by using the measurement data processing unit 108, and transmits the display signal representing the reconstructed image to the display device 24. The reconstructed image of the examinee is displayed on the display device 24.

The examination control device 20 comprises an examination table drive condition setting unit 120, an examination table control signal generation unit 122, an examination table control signal output unit 124, and a calibration data generation unit 126, as components related to the movement control of the tabletop 14A.

The examination table drive condition setting unit 120 sets a movement condition of the tabletop 14A on which the examinee is placed, based on an imaging protocol. Examples of the movement condition include identification information of the examinee and a measurement target part of the examinee.

The examination table control signal generation unit 122 generates a movement control signal for the tabletop 14A to be applied to the examination table drive unit 52. By the movement control signal for the tabletop 14A, a moving distance in the up-down direction of the tabletop 14A, a moving distance in the lateral direction of the tabletop 14A, and a moving distance in the front-rear direction of the tabletop 14A are specified. A movement speed of the tabletop 14A in each direction is appropriately specified.

The examination table control signal output unit 124 transmits a drive control signal to the examination table drive unit 52. The examination table drive unit 52 moves the tabletop 14A in at least any of the up-down direction, the lateral direction, or the front-rear direction based on the drive control signal.

The calibration data generation unit 126 generates calibration data for correcting the distance information transmitted from the camera 27. The calibration data is applied to the correction of the distance from the camera 27 to the examinee, which is derived by using the camera 27. Details of the calibration data generation will be described below.

The examination control device 20 comprises a camera image acquisition unit 130, a camera image processing unit 132, a distance information acquisition unit 134, a distance information processing unit 136, an actual measurement data acquisition unit 138, and an actual measurement data processing unit 140, as components related to the generation of the calibration data.

The camera image acquisition unit 130 acquires a camera image generated by using the camera 27 shown in FIG. 2. The camera image may be a live view image or a still image at any timing.

The camera image processing unit 132 performs specified processing on the camera image. For example, the camera image processing unit 132 performs processing of generating a guide or the like to be superimposed and displayed on the camera image.

The camera image processing unit 132 transmits data representing the camera image or the like to the display signal generation unit 110. The display signal generation unit 110 generates a display signal representing the camera image or the like and transmits the display signal to the display device 24. The camera image or the like is displayed on the display device 24.

A two-dimensional coordinate system is applied to the camera image, and the position in the camera image is specified using coordinate values. An example of the two-dimensional coordinate system applied to the camera image is a two-dimensional orthogonal coordinate system having two axes orthogonal to each other. An origin of the two-dimensional orthogonal coordinate system may be any of four corners of the camera image.

The distance information acquisition unit 134 acquires a distance from the camera 27 to the subject as the distance information transmitted from the camera 27.

The distance information processing unit 136 performs specified processing on the distance information acquired by using the distance information acquisition unit 134. The distance information processing unit 136 transmits the distance information that has been subjected to the specified processing to the display signal generation unit 110. The display signal generation unit 110 generates a display signal representing the distance information and transmits the display signal to the display device 24. The distance information is displayed on the display device 24. An example of the distance information is text information representing the distance from the camera 27 to the subject.

In addition, the distance information processing unit 136 transmits the distance information to the calibration data generation unit 126. The distance information is used for generating calibration data in the calibration data generation unit 126.

The actual measurement data acquisition unit 138 acquires actual measurement data measured by the operator. For example, the actual measurement data acquisition unit 138 acquires actual measurement data that is measured by the operator using a measurement instrument and that is input by the operator using the input device 22.

The actual measurement data processing unit 140 performs specified processing on the actual measurement data acquired by using the actual measurement data acquisition unit 138. The actual measurement data processing unit 140 transmits the actual measurement data to the calibration data generation unit 126. The actual measurement data is used for generating calibration data in the calibration data generation unit 126. The actual measurement data processing unit 140 may transmit the actual measurement data acquired by using the actual measurement data acquisition unit 138 to the display signal generation unit 110 and display the actual measurement data on the display device 24.

The calibration data generation unit 126, the camera image acquisition unit 130, the camera image processing unit 132, the distance information acquisition unit 134, the distance information processing unit 136, the actual measurement data acquisition unit 138, and the actual measurement data processing unit 140 shown in FIG. 4 can function as components of a calibration data generation device that generates calibration data applied to the correction of the movement parameter of the tabletop 14A.

Regarding Hardware Configuration of Each Processing Unit

A hardware structure of a processing unit that executes various kinds of processing of the console unit 16 shown in FIG. 2 and the examination control device 20 shown in FIG. 4 is, for example, various processors as shown below.

Various processors include a CPU, which is a general-purpose processor that executes a program and functions as various processing units, GPU, a programmable logic device (PLD), which is a processor of which a circuit configuration can be changed after manufacture such as a field programmable gate array (FPGA), a dedicated electric circuit, which is a processor having a circuit configuration specially designed to execute specific processing such as an application specific integrated circuit (ASIC), and the like.

One processing unit may be configured of one of the various types of processors, or configured of a combination of two or more processors of the same type or different types. For example, one processing unit may be configured of a plurality of FPGAs, a combination of a CPU and an FPGA, or a combination of a CPU and a GPU. In addition, a plurality of processing units may be configured of one processor. As an example of configuring a plurality of processing units by one processor, first, as represented by a computer, such as a client or a server, there is a form in which one processor is configured by a combination of one or more CPUs and software and this processor functions as a plurality of processing units. Second, as represented by a system on chip (SoC), a processor that realizes the functions of the entire system including the plurality of processing units by using one integrated circuit (IC) chip is used. As described above, the various processing units are configured using one or more of the various processors as a hardware structure.

The hardware structure of these various processors is more specifically an electric circuit (circuitry) in which circuit elements such as semiconductor elements are combined.

Generation of Up-Down Movement Calibration Data

FIG. 5 is a flowchart showing a procedure of an up-down movement calibration data generation method. The movement of the tabletop 14A in the up-down direction represents the movement of the tabletop 14A in the up-down direction orthogonal to the installation surface PP of the examination table 14. For example, in a case in which the installation surface PP of the examination table 14 is a surface parallel to a horizontal plane, the up-down movement represents the movement of the tabletop 14A in a vertical upward direction and a vertical downward direction. The term “parallel” in the present specification is not limited to “strict parallel”, and may include “substantially parallel” that can be regarded as parallel. The term “orthogonal” may include “substantially orthogonal” as in the case of the “parallel”.

Hereinafter, for convenience of description, the lateral direction may be referred to as a DX direction, the front-rear direction may be referred to as a DY direction, and the up-down direction may be referred to as a DZ direction.

In generating the calibration data, a calibration data generation program is installed in advance in the calibration data generation unit 126, and a computer provided with a processor functioning as the calibration data generation unit 126 executes the calibration data generation program. The program is synonymous with software.

In a home position movement step S10, the examination control device 20 shown in FIG. 2 moves the tabletop 14A to a home position with respect to the examination table 14 installed at a position where the measurement of the examinee is started. The home position is a position where the tabletop 14A is at its lowest, and represents the lowest position of the tabletop 14A. After the home position movement step S10, the process proceeds to an angle-of-view adjustment step S12. The movement of the examination table 14 may be performed manually by the operator or the like, or the examination table 14 may be operated automatically or semi-automatically.

In the angle-of-view adjustment step S12, the operator visually recognizes the camera image of the tabletop 14A, and a position of a headrest of the tabletop 14A is checked. That is, in the angle-of-view adjustment step S12, it is checked that the headrest is present at an upper end of a screen of the display device 24 in the camera image of the tabletop 14A. In a case of confirming the position of the headrest in the camera image, it may be checked that the gantry 11 is shown at an upper end of the camera image.

In a case in which the headrest is not shown within a specified range in the camera image of the examination table 14, an attachment direction of the camera unit 26 is adjusted, and the attachment direction of the camera unit 26 is changed to a specified attachment direction.

In addition, in the angle-of-view adjustment step S12, the operator visually recognizes the camera image of the tabletop 14A, and it is checked whether the examination table 14 is included in an examination table position guide frame displayed on a display screen of the camera image.

Further, in the angle-of-view adjustment step S12, the operator visually recognizes the camera image of the tabletop 14A, and it is checked whether all three marks on a straight guide displayed on the display screen of the camera image are displayed on the tabletop 14A.

In a case in which the position of the examination table 14 does not satisfy the above condition, the position of the examination table 14 is adjusted to a position where the above condition is satisfied. Instead of adjusting the examination table 14, an attachment position of the camera 27 may be adjusted, or the adjustment of the examination table 14 and the adjustment of the attachment position of the camera 27 may be used in combination.

In a case in which the position of the examination table 14 satisfies the above condition, the examination control device 20 acquires a signal representing the completion of the angle of view adjustment. The signal representing the completion of the angle-of-view adjustment may be transmitted to the examination control device 20 by the operator operating the input device 22 or the like. After the angle-of-view adjustment step S12, the process proceeds to a home position tabletop height acquisition step S14. The examination table position guide frame, the guide, and the mark are shown in FIG. 9.

In the home position tabletop height acquisition step S14, a home position tabletop height M_low, which is a height from the installation surface PP of the examination table 14 to an upper surface of the tabletop 14A at the home position, is acquired. The home position tabletop height M_low is a value measured by the operator, and a value input using the input device 22 can be acquired. After the home position tabletop height acquisition step S14, the process proceeds to a home position camera-to-tabletop distance acquisition step S16.

In the home position camera-to-tabletop distance acquisition step S16, a home position camera-to-tabletop distance H_low, which is a distance from the camera 27 to the tabletop 14A at the home position, is acquired. The distance information transmitted from the camera 27 may be applied to the home position camera-to-tabletop distance H_low. In a case in which the value of the distance information transmitted from the camera 27 is changed, the home position camera-to-tabletop distance H_low may be an approximate median value of the changed value. The operator may input the value of the distance information displayed on the display device 24 using the input device 22 as the home position camera-to-tabletop distance H_low.

The order of the home position tabletop height acquisition step S14 and the home position camera-to-tabletop distance acquisition step S16 may be interchanged, or both steps may be executed in parallel. After the home position camera-to-tabletop distance acquisition step S16, the process proceeds to a highest position movement step S18.

In the highest position movement step S18, the examination control device 20 raises the tabletop 14A from the home position and moves the tabletop 14A to the highest position. After the highest position movement step S18, the process proceeds to a highest position tabletop height acquisition step S20. The tabletop 14A may be raised manually, automatically, or semi-automatically.

In the highest position tabletop height acquisition step S20, a highest position tabletop height M_high, which is a height from the installation surface PP of the examination table 14 to the upper surface of the tabletop 14A at the highest position, is acquired. The highest position tabletop height M_high can be acquired in the same manner as the home position tabletop height M_low. After the highest position tabletop height acquisition step S20, the process proceeds to a highest position camera-to-tabletop distance acquisition step S22.

In the highest position camera-to-tabletop distance acquisition step S22, a highest position camera-to-tabletop distance H_high, which is a distance from the camera 27 to the tabletop 14A at the highest position, is acquired. The highest position camera-to-tabletop distance H_high is derived using the function of the camera 27 in the same manner as the home position camera-to-tabletop distance H_low. After the highest position camera-to-tabletop distance acquisition step S22, the process proceeds to an up-down movement calibration data generation step S24.

In the up-down movement calibration data generation step S24, the calibration data generation unit 126 generates up-down movement calibration data by using the home position tabletop height M_low, the home position camera-to-tabletop distance H_low, the highest position tabletop height M_high, and the highest position camera-to-tabletop distance H_high.

After the up-down movement calibration data is generated in the up-down movement calibration data generation step S24, the procedure of the up-down movement calibration data generation method is ended.

The home position of the tabletop 14A described in the embodiment is an example of a first up-down position, and the highest position of the tabletop 14A is an example of a second up-down position. The upper surface of the tabletop 14A at the home position described in the embodiment is an example of a first plane, the upper surface of the tabletop 14A at the highest position is an example of a second plane, and the upper surface of the tabletop 14A is an example of a placement surface.

The home position camera-to-tabletop distance H_low described in the embodiment is an example of first distance information, and the highest position camera-to-tabletop distance H_high is an example of second distance information. The camera image at the home position described in the embodiment is an example of first plane information, and the camera image at the highest position is an example of second plane information. The up-down movement calibration data described in the embodiment is an example of calibration data for correcting the movement parameter of the tabletop.

Specific Example of Examination Table Height

FIG. 6 is an explanatory diagram of an examination table height. In FIG. 6, the home position and the highest position of the tabletop 14A at a position of the examination table 14 where the tabletop 14A starts to enter the imaging space 11A of the gantry 11 are schematically shown. The upper tabletop 14A shown in FIG. 6 shows a state in which the upper tabletop 14A is stopped at the highest position. The lower tabletop 14A shown in FIG. 6 shows a state in which the lower tabletop 14A is stopped at the home position. The plus DY direction shown in FIG. 6 is a backward direction, and the minus DY direction is a forward direction.

The camera 27 shown in FIG. 6 is installed directly above a center position CP of the tabletop 14A at the home position, and the camera 27 is directed directly downward and is not inclined with respect to the horizontal plane. That is, an imaging optical axis OP of the camera 27 passes through the center position CP of the tabletop 14A and faces a direction orthogonal to the installation surface PP of the examination table 14.

However, in the actual imaging room 17A, the camera 27 may not be able to be installed directly above the center position CP of the tabletop 14A. For example, in a case in which an illumination device, a projector, or the like is installed directly above the center position CP of the tabletop 14A, the illumination device or the like interferes with the camera 27. In such a case, the camera 27 is installed to be shifted in at least one of the front-rear direction or the left-right direction.

Specific Example of Camera Image Visually Recognized in Angle-of-View Adjustment Step

FIG. 7 is a schematic diagram of a screen on which a camera image is displayed. A camera image display screen 200 shown in FIG. 7 is a display screen for the camera image to be displayed on the display device 24. The camera image shown in FIG. 7 is a live view image.

In the angle-of-view adjustment step S12 shown in FIG. 5, the operator visually recognizes the camera image display screen 200 to check whether or not the gantry 11 and a headrest 14B are shown on an upper side of the camera image display screen 200.

In the camera image display screen 200 shown in FIG. 7, the imaging space 11A and the headrest 14B of the gantry 11 are shown on the upper side of the camera image display screen 200, and the adjustment of the installation direction of the camera 27 is not necessary in the angle-of-view adjustment step S12.

FIG. 8 is a schematic diagram of another example of a screen on which a camera image is displayed. A camera image shown on a camera image display screen 202 shown in FIG. 8 displays a headrest 14C having a different shape from the headrest 14B shown in FIG. 7. In the camera image display screen 202 shown in FIG. 8, the imaging space 11A of the gantry 11 and the headrest 14C are shown on an upper side of the camera image display screen 202, and the adjustment of the installation direction of the camera 27 is not necessary in the angle-of-view adjustment step S12.

Specific Example of Guide Superimposed and Displayed on Camera Image

FIG. 9 is a schematic diagram showing a specific example of a guide displayed in a superimposed manner on a camera image. A camera image display screen 204 shown in FIG. 9 is displayed on the display device 24 in the angle-of-view adjustment step S12 shown in FIG. 5. The camera image display screen 204 displays a camera image in which the tabletop 14A of the examination table 14 is imaged, and an examination table position guide frame EF, a lateral guide XG, and a front-rear guide YG are superimposed and displayed on the camera image.

In addition, in the camera image display screen 204, a first mark Mt, a second mark Mc, and a third mark Mb, which represent the measurement position of the distance from the camera 27 to the tabletop 14A, are superimposed and displayed on the camera image by being superimposed on the front-rear guide YG.

The examination table position guide frame EF represents both ends in the lateral direction of a region in which the examination table 14 is disposed. In the angle-of-view adjustment step S12 shown in FIG. 5, the operator visually recognizes the camera image display screen 204 to adjust the position of the examination table 14 in the lateral direction, and disposes the examination table 14 between two examination table position guide frames EF. In a case in which the camera 27 is shifted in the left-right direction, the examination table position guide frame EF and the examination table 14 need only be parallel to each other in the left-right direction.

The lateral guide XG represents a center position in the front-rear direction in the camera image. The front-rear guide YG represents a center position in the lateral direction in the camera image. The second mark Mc is displayed at an intersection of the lateral guide XG and the front-rear guide YG. The second mark Mc represents a center position of the camera image and represents a measurement position at a distance from the camera 27 to the center position CP of the tabletop 14A.

In the angle-of-view adjustment step S12 shown in FIG. 5, the operator visually recognizes the camera image to check whether or not the first mark Mt, the second mark Mc, and the third mark Mb are superimposed and displayed on the tabletop 14A. In a case in which the first mark Mt, the second mark Mc, and the third mark Mb are not superimposed and displayed on the tabletop 14A, the position of the examination table 14 or the position of the camera 27 is adjusted, and the examination table 14 is disposed at a position where the first mark Mt, the second mark Mc, and the third mark Mb are superimposed and displayed on the tabletop 14A.

Specific Example of Up-Down Movement Calibration Data

FIG. 10 is a graph showing an example of up-down movement calibration data. A horizontal axis of a graph G1 shown in FIG. 10 represents a distance from the camera 27 to the tabletop 14A. A vertical axis of the graph G1 represents an actual measurement value of a distance from the installation surface PP of the examination table 14 to the tabletop 14A. The unit of the distance from the camera 27 to the tabletop 14A and the unit of the distance from the installation surface PP of the examination table 14 to the tabletop 14A are millimeters. In addition, for convenience, in the graph G1, the horizontal axis is referred to as an x-axis, and the vertical axis is referred to as a y-axis. The same applies to a graph G2 shown in FIG. 14.

A linear function F₁ represented by the graph G1 is derived by using the home position tabletop height M_low, the home position camera-to-tabletop distance H_low, the highest position tabletop height M_high, and the highest position camera-to-tabletop distance H_high. The calibration data generation unit 126 shown in FIG. 4 derives a set of a value of a slope a₁ and a value of an intercept b₁ of the y-axis, which is a value axis, of the linear function F₁ as the up-down movement calibration data.

FIG. 11 is an explanatory diagram of a mathematical equation representing a linear function of the graph shown in FIG. 10. The linear function F₁ is represented by Equation 1 shown in FIG. 11. The slope a₁ used in Equation 1 is represented by Equation 2. In addition, the y-axis intercept b₁ used in Equation 1 is represented by Equation 3.

The linear function F₁ shown in FIGS. 10 and 11 is used for deriving a distance camera_iso_mm from the camera 27 to the ISO center in the up-down direction. For example, in a case in which the distance from the installation surface PP of the examination table 14 to the ISO center in the up-down direction is 1234 millimeters, in the linear function F₁, a value of x in a case in which y=1234 is the distance camera_iso_mm from the camera 27 to the ISO center in the up-down direction. That is, the linear function F₁ is represented by x=(y−b₁)/a₁, and camera_iso_mm=(1234−b₁)/a₁.

The calibration data is applied to the derivation of a movement amount of the tabletop 14A in the up-down direction. A distance camera_patient_mm from the camera 27 to the examinee is obtained using the camera 27. A movement amount move_height_mm of the tabletop 14A in the up-down direction is calculated by subtracting the distance camera_iso_mm from the camera 27 to the ISO center from the distance camera_patient_mm from the camera 27 to the examinee.

That is, the movement amount move_height_mm of the tabletop 14A in the up-down direction is represented by (move_height_mm)=(camera_iso_mm)−(camera_point_mm).

Specific Example of Generating Front-Rear Lateral Movement Calibration Data

FIG. 12 is a flowchart showing a procedure of a front-rear lateral movement calibration data generation method. In a home position movement step S100, the examination control device 20 shown in FIG. 2 moves the tabletop 14A to the home position, similarly to the home position movement step S10 shown in FIG. 5. After the home position movement step S100, the process proceeds to a home position tabletop both-ends coordinate acquisition step S102.

In the home position tabletop both-ends coordinate acquisition step S102, the examination control device 20 acquires coordinates of both ends of the tabletop 14A in the lateral direction. Specifically, a two-dimensional orthogonal coordinate system that is specified in the camera image and that is based on a DX axis along the lateral direction and a DY axis along the front-rear direction is applied to acquire a coordinate value LowTableLeftPointX of one end of the tabletop 14A in the DX direction and a coordinate value LowTableRightPointX of the other end. The coordinate values are represented by the number of pixels.

In the home position tabletop both-ends coordinate acquisition step S102, the operator may operate a mouse to click both ends of the tabletop 14A in the DX direction in the camera image as a mouse event to acquire the coordinate values of both ends of the tabletop 14A in the DX direction. After the home position tabletop both-ends coordinate acquisition step S102, the process proceeds to a home position tabletop center position specification step S104.

In the home position tabletop center position specification step S104, the position of the tabletop 14A overlapping the center position of the camera image is marked using the front-rear guide YG and the lateral guide XG superimposed and displayed on the camera image as markers. After the home position tabletop center position specification step S104, the process proceeds to a highest position movement step S106.

In the highest position movement step S106, the examination control device 20 raises the tabletop 14A from the home position and moves the tabletop 14A to the highest position, similarly to the highest position movement step S18 shown in FIG. 5. After the highest position movement step S106, the process proceeds to a highest position tabletop both-ends coordinate acquisition step S108.

In the highest position tabletop both-ends coordinate acquisition step S108, the examination control device 20 acquires a coordinate value HighTableLeftPointX of one end of the tabletop 14A in the DX direction at the highest position and a coordinate value HighTableRightPointX of the other end, similarly to the home position tabletop both-ends coordinate acquisition step S102. After the highest position tabletop both-ends coordinate acquisition step S108, the process proceeds to a highest position tabletop center position specification step S110.

In the highest position tabletop center position specification step S110, the position of the tabletop 14A overlapping the center position of the camera image is marked using the front-rear guide YG and the lateral guide XG superimposed and displayed on the camera image as markers, similarly to the home position tabletop center position specification step S104. After the highest position tabletop center position specification step S110, the process proceeds to a deviation amount acquisition step S112.

In the deviation amount acquisition step S112, the operator measures a distance between the marking at the home position and the marking at the highest position in the DX direction and the DY direction.

That is, in the deviation amount acquisition step S112, a DX deviation amount UpTableZureX representing the deviation amount of the center position of the camera image due to the up-and-down movement of the tabletop 14A in the DX direction and a DY deviation amount UpTableZureY representing the deviation amount of the center position of the camera image due to the up-and-down movement of the tabletop 14A in the DY direction are acquired. After the deviation amount acquisition step S112, the process proceeds to a pre-forward movement center position specification step S114.

In the pre-forward movement center position specification step S114, the center position in the DX direction of the tabletop 14A and the center position in the DY direction of the tabletop 14A in the camera image are specified at a pre-forward movement position. That is, in the pre-forward movement center position specification step S114, the center position in the DX direction of the tabletop 14A in the camera image is marked and the center position in the DY direction of the tabletop 14A in the camera image is marked, by using the lateral guide XG and the front-rear guide YG superimposed and displayed on the camera image as markers. After the pre-forward movement center position specification step S114, the process proceeds to a forward movement step S116.

In the forward movement step S116, the tabletop 14A is moved in the forward direction to a position where the tabletop 14A hits a light localizer indicating the ISO center. After the forward movement step S116, the process proceeds to a post-forward movement center position specification step S118.

In the post-forward movement center position specification step S118, the center position in the DX direction of the tabletop 14A and the center position in the DY direction of the tabletop 14A in the camera image are specified at a post-forward movement position, similarly to the pre-forward movement center position specification step S114. After the post-forward movement center position specification step S118, the process proceeds to an ISO center distance derivation step S120.

In the ISO center distance derivation step S120, an ISO center distance ISOcenterDistanceX in the DX direction is derived based on the center position in the DX direction of the tabletop 14A specified in the pre-forward movement center position specification step S114 and the center position in the DX direction of the tabletop 14A specified in the post-forward movement center position specification step S118.

In addition, in the ISO center distance derivation step S120, an ISO center distance ISOcenterDistanceY in the DY direction is derived based on the center position in the DY direction of the tabletop 14A specified in the pre-forward movement center position specification step S114 and the center position in the DY direction of the tabletop 14A specified in the post-forward movement center position specification step S118. After the ISO center distance derivation step S120, the process proceeds to a front-rear lateral movement calibration data generation step S122.

In the front-rear lateral movement calibration data generation step S122, the calibration data generation unit 126 calculates a home position length-pixel conversion value LowTableMpp for converting the number of pixels at the home position into a length, based on the coordinate value LowTableLeftPointX of one end in the DX axis of the tabletop 14A at the home position and the coordinate value LowTableRightPointX of the other end.

In addition, in the front-rear lateral movement calibration data generation step S122, the calibration data generation unit 126 calculates a highest position length-pixel conversion value HighTableMpp for converting the number of pixels at the highest position into a length by using the coordinate value HighTableLeftPointX of one end in the DX axis of the tabletop 14A at the highest position and the coordinate value HighTableRightPointX of the other end.

Further, in the front-rear lateral movement calibration data generation step S122, the calibration data generation unit 126 generates front-rear lateral movement calibration data by using the home position camera-to-tabletop distance H_low representing the distance from the camera 27 to the tabletop 14A at the home position and the highest position camera-to-tabletop distance H_high representing the distance from the camera 27 to the tabletop 14A at the highest position.

After the front-rear lateral movement calibration data is generated in the front-rear lateral movement calibration data generation step S122, the procedure of the front-rear lateral movement calibration data generation method is ended.

Specific Example of Tabletop Both-Ends Coordinate Acquisition

FIG. 13 is an explanatory diagram of tabletop both-ends coordinate acquisition. In FIG. 13, a display screen 206 of the camera image is schematically shown. A guide for the tabletop 14A in the DX direction may be a boundary between a side cover 14D and the tabletop 14A, which is shown using a broken line. A left end of the tabletop 14A in FIG. 13 corresponds to the coordinate value LowTableLeftPointX and the coordinate value HighTableLeftPointX. In addition, a right end of the tabletop 14A corresponds to the coordinate value LowTableRightPointX and the coordinate value HighTableRightPointX.

In a case in which a total width of the tabletop 14A in the DX direction is denoted by H_T, the home position length-pixel conversion value LowTableMpp is represented by (LowTableMpp)=H_T/{(LowTableRightPointX)−(LowTableLeftPointX)}. The coordinate value LowTableRightPointX has a value exceeding a value of the coordinate value LowTableLeftPointX.

In addition, the highest position length-pixel conversion value HighTableMpp is represented by (HighTableMpp)=H_T/{(HighTableRightPointX)−(HighTableLeftPointX)}. The coordinate value HighTableRightPointX has a value exceeding a value of the coordinate value HighTableLeftPointX.

Specific Example of Front-Rear Lateral Movement Calibration Data

FIG. 14 is a graph showing an example of front-rear lateral movement calibration data. A horizontal axis of a graph G2 shown in FIG. 14 represents a distance from the camera 27 to the tabletop 14A. The unit of the horizontal axis of the graph G2 is millimeters. A vertical axis of the graph G2 represents a distance mpp on the tabletop 14A per pixel of the camera image. The unit of the vertical axis of the graph G2 is millimeters per pixel.

A linear function F₂ represented by the graph G2 is derived by using the home position camera-to-tabletop distance H_low, the highest position camera-to-tabletop distance H_high, the home position length-pixel conversion value LowTableMpp, and the highest position length-pixel conversion value HighTableMpp. The calibration data generation unit 126 shown in FIG. 4 derives a set of a value of a slope a₂ and a value of an intercept b₂ of the y-axis, which is a value axis, of the linear function F₂ as the front-rear lateral movement calibration data.

FIG. 15 is an explanatory diagram of a mathematical equation representing a linear function of the graph shown in FIG. 14. The linear function F₂ shown by a graph G2 in FIG. 14 is represented by Equation 4 shown in FIG. 15. The slope a₂ used in Equation 4 is represented by Equation 5. In addition, the y-axis intercept b₂ used in Equation 4 is represented by Equation 6.

The home position length-pixel conversion value LowTableMpp described in the embodiment is an example of home position conversion information representing a conversion relationship between the number of pixels and the distance at the home position. The highest position length-pixel conversion value HighTableMpp described in the embodiment is an example of highest position conversion information representing a conversion relationship between the number of pixels and the distance at the highest position.

Specific Example of Marking at Home Position

FIG. 16 is an explanatory diagram of an example of marking of a center position at the home position. In a camera image display screen 208 shown in FIG. 16, a home position DX marking HXM and a home position DY marking HYM applied to the tabletop 14A in the home position tabletop center position specification step S104 shown in FIG. 12 are shown.

The home position DX marking HXM is located at a position along the front-rear guide YG and is provided at a position intersecting the lateral guide XG. The home position DY marking HYM is located at a position along the lateral guide XG and is provided at a position intersecting the front-rear guide YG.

FIG. 17 is an explanatory diagram of an example of marking of a camera center at the highest position. FIG. 17 shows a highest position DX marking MXM and a highest position DY marking MYM applied to the tabletop 14A in the highest position tabletop center position specification step S110 shown in FIG. 12.

The highest position DX marking MXM is located at a position along the front-rear guide YG and is provided at a position intersecting the lateral guide XG. The highest position DY marking MYM is located at a position along the lateral guide XG and is provided at a position intersecting the front-rear guide YG.

Specific Example of Acquisition of Acquisition of Deviation Amount of Tabletop Center Position

FIG. 18 is an explanatory diagram of acquisition of a deviation amount of tabletop center position. FIG. 18 shows the home position DX marking HXM, the home position DY marking HYM, the highest position DX marking MXM, and the highest position DY marking MYM shown in FIG. 17 in an enlarged manner.

In the deviation amount acquisition step S112 shown in FIG. 12, the operator measures a distance between the home position DX marking HXM and the highest position DX marking MXM in the DX direction, and derives a DX deviation amount UpTableZureX. The unit of the DX deviation amount UpTableZureX is millimeters.

In a case in which the home position DX marking HXM is positioned on the right side with respect to the highest position DX marking MXM, the DX deviation amount UpTableZureX is set to a value of minus. In addition, in a case in which the home position DX marking HXM is positioned on the left side with respect to the highest position DX marking MXM, the DX deviation amount UpTableZureX is set to a value of plus.

FIG. 18 shows an aspect in which a distance between the markings is measured based on a right end of each marking as a reference, but a left end of each marking may be used as a reference, or a center of each marking may be used as a reference.

In addition, in the deviation amount acquisition step S112, the operator measures a distance between the home position DY marking HYM and the highest position DY marking MYM in the DY direction, and derives a DY deviation amount UpTableZureY The unit of the DY deviation amount UpTableZureY is millimeters.

In a case in which the home position DY marking HYM is positioned on the upper side with respect to the highest position DY marking MYM, the DY deviation amount UpTableZureY is set to a value of minus. In addition, in a case in which the home position DY marking HYM is positioned on the lower side with respect to the highest position DY marking MYM, the DY deviation amount UpTableZureY is set to a value of plus.

FIG. 18 shows an aspect in which a distance between the markings is measured based on an upper end of each marking as a reference, but a lower end of each marking may be used as a reference, or a center of each marking may be used as a reference.

Specific Example of Marking in Post-Forward Movement Center Position Specification Step

FIG. 19 is an explanatory diagram of an example of marking after the tabletop is moved forward. In FIG. 19, a frame CIF representing a display range of the camera image, a lateral guide XG superimposed and displayed on the camera image, and a front-rear guide YG are shown.

In the post-forward movement center position specification step S118 shown in FIG. 12, the operator applies a forward movement position X marking FPXM along the front-rear guide YG and applies a forward movement position Y marking FPYM along the lateral guide XG to the tabletop 14A.

FIG. 20 is an explanatory diagram of an example of a difference value between a camera center and an ISO center. FIG. 20 shows a DX difference value ISOcenterDistanceX, which is a difference value between the camera center and the ISO center in the lateral direction, and a DY difference value ISOcenterDistanceY, which is a difference value between the camera center and the ISO center in the front-rear direction.

A light localizer shown in FIG. 20 is a ray representing the ISO center, and is used as a marker for alignment between the examinee and the center of imaging. A laser beam or the like is applied as the light localizer.

The operator measures the DX difference value ISOCenterDistanceX and the DY difference value ISOCenterDistanceY, and inputs the measured values to the examination control device 20. In a case in which the camera 27 is attached directly above a position of the ISO center in the lateral direction, a measured value of the DX difference value ISOcenterDistanceX is theoretically zero. The units of the DX difference value ISOCenterDistanceX and the DY difference value ISOCenterDistanceY are millimeters.

Specific Example of Calibration in Lateral Direction and Front-Rear Direction

FIG. 21 is a schematic diagram showing a specific example of calibration in a lateral direction and a front-rear direction. FIG. 21 schematically shows a camera image of the examinee placed on the tabletop 14A of the examination table 14.

The alignment between a scan start position of the examinee and the ISO center, in which the calibration data is used, is performed according to the following procedure. First, coordinate values (middle_line, middle_line_st) of the scan start position in a front-rear lateral plane are estimated from the camera image. Here, an origin of a two-dimensional orthogonal coordinate system applied to the camera image is set to an upper left end of the camera image. The number of pixels from the origin is applied as the coordinate value.

Next, the value of the slope a₂ and the value of the y-axis intercept b₂ of the linear function F₂ shown in FIG. 14 are read. An estimated value H__estimate of the distance from the camera 27 to the tabletop 14A at a height of the tabletop 14A at which the scan start position is estimated is substituted for x in Equation 4 representing the linear function F₂ shown in FIG. 15, and a length-pixel conversion value Estimate_TableMpp at the height of the tabletop 14A at which the scan start position is estimated is calculated. That is, the length-pixel conversion value Estimate_TableMpp is represented by (Estimate_TableMpp)=a₂×(H__estimate)+b₂.

Next, the number of pixels from the center position of the camera image to the scan start position is converted into a distance in a unit such as millimeters, by using the length-pixel conversion value Estimate_TableMpp. The center position of the camera image is an intersection of the lateral guide XG and the front-rear guide YG shown in FIG. 20.

A distance middle_line_mm from the center position of the camera image in the lateral direction to the scan start position is represented by (middle_line_mm)={PNX−(middle_line)}×(Estimate_TableMpp). PNX is a half value of the number of pixels in the lateral direction of the camera image. In a case in which the number of pixels in the lateral direction of the camera image is 600, PNX is 300.

In addition, a distance middle_line_st_mm from the center position of the camera image in the front-rear direction to the scan start position is represented by (middle_line_st_mm)={(middle_line_st)−PNY}×Estimate_TableMpp. PNY is a half value of the number of pixels in the front-rear direction of the camera image. In a case in which the number of pixels in the front-rear direction of the camera image is 1200, PNY is 600.

The distance from the center position of the camera image to the scan start position is a value estimated at the height of the tabletop 14A at which the scan start position is estimated. This value is converted into a value at the highest position of the tabletop 14A.

First, a distance high_table_middle_line_mm from the center position of the camera image in the lateral direction to the scan start position at the highest position is represented by (high_table_middle_line_mm)=(middle_line_mm)+{(H__estimate−H_high)/(H_low−H_high)}×(UpTableZureX).

In addition, a distance high_table_middle_line_st_mm from the center position of the camera image in the front-rear direction to the scan start position at the highest position is represented by (high_table_middle_line_st_mm)=(middle_line_st_mm)+{(H__estimate−H_high)/(H_low−H_high)}×(UpTableZureY). The scan start position described in the embodiment is an example of a measurement start position specified for the examinee.

Next, a moving distance move_shift_mm of the tabletop 14A in the lateral direction and a moving distance move_position_mm of the tabletop 14A in the front-rear direction are calculated. The moving distance move_shift_mm of the tabletop 14A in the lateral direction is represented by (move_shift_mm)=(ISOcenterDistanceX)−(high_table_middle_line_mm).

In addition, the moving distance move_position_mm of the tabletop 14A in the front-rear direction is represented by (move_position_mm)=(ISOcenterDistanceY)−(high_table_middle_line_st_mm).

In a case in which the value of the moving distance move_shift_mm of the tabletop 14A in the lateral direction is minus, the tabletop 14A is moved in a right direction in FIG. 21. On the other hand, in a case in which the value of the moving distance move_shift_mm is plus, the tabletop 14A is moved in a left direction in FIG. 21.

The moving distance move_position_mm of the tabletop 14A in the front-rear direction is always in the minus direction, and the tabletop 14A is moved in the forward direction.

Specific Example of Calibration in Case in which Camera is Installed in Inclined State

FIG. 22 is a schematic diagram of a distance from a camera to the tabletop in a case in which the camera is inclined with respect to an installation surface. The camera 27 may be inclined with respect to the installation surface PP so that the tabletop 14A is included in a frame of a camera image. For example, the imaging optical axis OP of the camera 27 is rotated about a rotation axis parallel to the lateral direction, and the inclination of the camera 27 is adjusted in a range of, for example, plus 5 degrees to minus 5 degrees.

In a case in which the camera 27 is inclined and adjusted, the distance from the camera 27 to the tabletop 14A varies depending on the position of the tabletop 14A in the front-rear direction. Therefore, in the adjustment of the attachment position in the front-rear direction and in the lateral direction, the distance from the camera 27 to the tabletop 14A for each position of the tabletop 14A in the front-rear direction is adopted.

That is, the distance from the camera 27 to the tabletop 14A affects the accuracy in calculating the moving distance of the tabletop 14A in the front-rear direction. Therefore, it is necessary to adjust the attachment direction of the camera 27 in which the inclination of the camera 27 with respect to the installation surface PP is considered.

In a case in which an orientation of the camera 27 is adjusted so that the imaging optical axis OP of the camera 27 is orthogonal to the installation surface PP, a distance from the camera 27 to a center position of the camera image shown in the camera image is measured as the distance from the camera 27 to the tabletop 14A. That is, the linear function F₁ shown in FIG. 10 and the linear function F₂ shown in FIG. 14 are based on the center position of the camera image.

In a case in which the orientation of the camera 27 with respect to the installation surface PP is adjusted to be inclined within a specified range, a distance from the camera 27 to the tabletop 14A measured at a position different from the center position of the camera image is converted into a value at the center position of the camera image. A linear function used for this conversion is prepared.

FIG. 23 is an explanatory diagram showing an example of a measurement position on the tabletop. A first mark Mt, a second mark Mc, and a third mark Mb shown in FIG. 23 are used for deriving the linear function.

At the home position of the examination table 14, a distance from the camera 27 to the second mark Mc is denoted by D_center, a distance from the camera 27 to the first mark Mt is denoted by D_minus, and a distance from the camera 27 to the third mark Mb is denoted by D_plus. Each of the above distances is acquired as distance information of the camera 27. The unit of each distance is millimeters.

A linear function F₃ on a minus side in the front-rear direction is represented by z=a₃×y. Each of z and y in the mathematical equation representing the linear function F₃ represents a value in the up-down direction and a value in the front-rear direction. The same applies to the following linear function F₄.

In a case in which the number of pixels representing a distance from the second mark Mc to the first mark Mt in the front-rear direction is set to −500 pixels, a slope a₃ of the linear function F₃ is represented by a₃={(D_center)−(D_minus)}/{0−(−500)}={(D_center)−(D_minus)}/500.

Similarly, the linear function F₄ on a plus side in the front-rear direction is represented by z=a₄×y. In a case in which the number of pixels representing a distance from the second mark Mc to the third mark Mb in the front-rear direction is set to +500 pixels, a slope a₄ of the linear function F₄ is represented by a₄={(D_center)−(D_plus)}/{0−(+500)}={(D_center)−(D_plus)}/(−500). Here, 0 in the mathematical equation representing the slope a₃ of the linear function F₃ and in the mathematical equation representing the slope a₄ of the linear function F₄ means the coordinate value of the center position of the camera image.

That is, the number of pixels from the second mark Mc to the first mark Mt and the number of pixels from the second mark Mc to the third mark Mb represent that the second mark Mc is used as a reference. The slope a₃ of the linear function F₃ and the slope a₄ of the linear function F₄ are stored as calibration data.

FIG. 24 is a schematic diagram of calibration in a case in which the camera is inclined with respect to the installation surface. In a case in which the camera is installed in a state of being inclined with respect to the installation surface PP, a correction value with respect to the estimated value HN__estimate of the distance from the camera 27 to the tabletop 14A or a correction value with respect to the estimated value HP__estimate of the distance from the camera 27 to the tabletop 14A is calculated.

In the calculation of the correction value, a coordinate value Y_estimate in the front-rear direction of the estimated value MPN in a case in which the estimated value HN__estimate of the distance from the camera 27 to the tabletop 14A is estimated at the estimated position MPN on the tabletop 14A is calculated. The estimated position MPN is a position on the minus side in the front-rear direction with respect to the center position of the camera image. Here, the center position of the camera image matches the center position of the camera image in a case in which the camera 27 is not inclined.

In a case in which the coordinate value Y_estimate in the front-rear direction of the estimated position MPN is a value of minus, the coordinate value Y_estimate is substituted for y of the linear function F₃, and a correction value ZCN is calculated as the value of z of the linear function F₃.

The estimated value H__estimate of the distance from the camera 27 to the tabletop 14A at the center position of the camera image is represented by (H__estimate)−(HN__estimate)−(ZCN) by using the estimated value HN__estimate of the distance from the camera 27 to the tabletop 14A at the estimated position MPN and the correction value ZCN.

Similarly, in a case in which the estimated value HP__estimate of the distance from the camera 27 to the tabletop 14A is estimated at an estimated position MPP on the plus side in the front-rear direction and the coordinate value Y_estimate in the front-rear direction of the estimated position MPP is a value of plus, the coordinate value Y_estimate is substituted for y of the linear function F₄, and a correction value ZCP is calculated as the value of z of the linear function F₄.

The estimated value H__estimate of the distance from the camera 27 to the tabletop 14A at the center position of the camera image is represented by (H__estimate)=(HP__estimate)+(ZCP) by using the estimated value HP__estimate of the distance from the camera 27 to the tabletop 14A at the estimated position MPP and the correction value ZCP.

In a case in which the camera 27 is inclined with respect to the installation surface PP, the estimated value of the distance from the camera 27 to the tabletop 14A at an estimated position away from the center position of the camera image is corrected to the estimated value H__estimate of the distance from the camera 27 to the tabletop 14A at the center position of the camera image, and calibration in the front-rear direction and in the lateral direction is performed using the estimated value H__estimate.

The correction value ZCN and the correction value ZCP described in the embodiment are examples of a variation in the distance from the sensor to the tabletop. The linear function F₃ and the linear function F4 described in the embodiment are examples of second conversion information.

Effects of Embodiment

The examination control device 20 according to the embodiment can obtain the following effects.

[1]

The camera 27 installed on the ceiling of the imaging room 17A is adjusted in position and posture such that the entire tabletop 14A is shown in the camera image and the headrest 14B and the like are reflected at a specified position in the camera image.

At the home position of the tabletop 14A provided in the examination table 14, the home position camera-to-tabletop distance H_low, which is the distance from the camera 27 to the tabletop 14A of the examination table 14, is measured using the camera 27 installed on the ceiling of the imaging room 17A, and the operator measures the home position tabletop height M_low, which is a height from the installation surface PP of the examination table 14 to the upper surface of the tabletop 14A.

At the highest position where the tabletop 14A is at its highest, the highest position camera-to-tabletop distance H_high is measured as a distance from the camera 27 to the tabletop 14A of the examination table 14, and the operator measures the highest position tabletop height M_high, which is a height from the installation surface PP of the examination table 14 to the upper surface of the tabletop 14A.

From the measurement results, the linear function F₁ representing a relationship between the distance from the camera 27 to the tabletop 14A and the distance from the installation surface PP to the tabletop 14A is derived. A combination of the slope a₁ and the y-axis intercept b₁ of the linear function F₁ is derived and stored as the up-down direction calibration data.

As a result, even in a case in which the position where the camera 27 is installed is shifted from a position specified in advance, it is possible to correct the moving distance of the tabletop 14A in the up-down direction based on the measurement result of the distance from the camera 27 to the examinee.

[2]

At the home position of the tabletop 14A, the number of pixels corresponding to the entire length of the tabletop 14A in the lateral direction is derived from the coordinate values of both ends in the lateral direction of the tabletop 14A shown in the camera image. The total length of the tabletop 14A in the lateral direction is divided by the derived number of pixels to calculate the home position length-pixel conversion value LowTableMpp.

At the highest position of the tabletop 14A, the number of pixels corresponding to the entire length of the tabletop 14A in the lateral direction is derived from the coordinate values of both ends in the lateral direction of the tabletop 14A shown in the camera image. The total length of the tabletop 14A in the lateral direction is divided by the derived number of pixels to calculate the highest position length-pixel conversion value HighTableMpp.

From the measurement results, the linear function F₂ representing a relationship between the distance from the camera 27 to the tabletop 14A and the length-pixel conversion value is derived. A set of the slope a₂ and the intercept b₂ of the y-axis, which is a value axis, of the linear function F₂ is derived and stored as the front-rear lateral direction calibration data.

As a result, at any height of the tabletop 14A, the number of pixels from the estimated center position of the camera image to the scan start position in the camera image is converted into a distance in a unit such as millimeters.

[3]

In the lateral direction, the deviation amount UpTableZureX between the center position of the camera image at the home position of the tabletop 14A and the center position of the camera image at the highest position of the tabletop 14A is measured.

As a result, in the lateral direction, using the deviation amount UpTableZureX, the distance middle_line_mm from the center position of the camera image at any height of the tabletop 14A to the scan start position is converted into the distance high_table_middle_line_mm from the center position of the camera image at the highest position of the tabletop 14A to the scan start position.

In addition, in the front-rear direction, the deviation amount UpTableZureY between the center position of the camera image at the home position of the tabletop 14A and the center position of the camera image at the highest position of the tabletop 14A is measured.

As a result, in the front-rear direction, using the deviation amount UpTableZureY, the distance middle_line_st_mm from the center position of the camera image at any height of the tabletop 14A to the scan start position is converted into the distance high_table_middle_line_st_mm from the center position of the camera image at the highest position of the tabletop 14A to the scan start position.

[4]

At the highest position of the tabletop 14A, the distance ISOcenterDistanceX between the center of the camera image in the lateral direction and the ISO center is measured.

As a result, the moving distance move_shift_mm of the tabletop 14A in the lateral direction is calculated from the distance high_table_middle_line_mm from the center position of the camera image to the scan start position.

Similarly, at the highest position of the tabletop 14A, the distance ISOcenterDistanceY between the center of the camera image in the front-rear direction and the ISO center is measured.

As a result, the moving distance move_position_mm of the tabletop 14A in the front-rear direction is calculated from the distance high_table_middle_line_st_mm from the center position of the camera image to the scan start position.

[5]

For the minus side in the front-rear direction, a minus side measurement position separated from the center position of the camera image by a specified number of pixels is specified. The slope a₃ of the linear function F₃ on the minus side in the front-rear direction is specified by using the distance D_center from the camera 27 to the center position of the camera image, the distance D_minus from the camera 27 to the minus side measurement position, and the number of pixels from the center position of the camera image to the minus side measurement position.

As a result, even in a case in which the camera 27 is inclined to the minus side in the front-rear direction with respect to the installation surface PP, the moving distance of the tabletop 14A in the front-rear direction can be corrected based on the distance from the camera 27 to the tabletop 14A at the center position of the camera image.

For the plus side in the front-rear direction, a plus side measurement position separated from the center position of the camera image by a specified number of pixels is specified. The slope a₄ of the linear function F₄ on the plus side in the front-rear direction is specified by using the distance D_center from the camera 27 to the center position of the camera image, the distance D_plus from the camera 27 to the plus side measurement position, and the number of pixels from the center position of the camera image to the plus side measurement position.

As a result, even in a case in which the camera 27 is inclined to the plus side in the front-rear direction with respect to the installation surface PP, the moving distance of the tabletop 14A in the front-rear direction can be corrected based on the distance from the camera 27 to the tabletop 14A at the center position of the camera image.

Another Embodiment of Calculation of Movement Amount of Examination Table

FIG. 25 is an explanatory diagram of a scanogram imaging start position line in a case in which ahead is imaged. FIG. 25 shows a camera image of the examination table 14 on which the examinee is placed. CIF shown in FIG. 25 represents a frame of the camera image. A scanogram imaging start position is synonymous with the scan start position shown in FIG. 21.

In a case in which the head of the examinee is measured, a scanogram imaging start position line SSL is set at a position away from a parietal part Par in an IN direction of the parietal part Par of the examinee. The IN direction is a movement direction in a case in which the examination table 14 moves toward the inside of the gantry, and is an upward direction in the camera image.

In a case in which the irradiation is performed by the light localizer after the tabletop 14A of the examination table 14 is automatically adjusted based on the camera image, the laser light as the light localizer is emitted at a position deviated in the IN direction from the parietal part Par with respect to the center position of the gantry directly below a tube where it has to be irradiated with the laser light.

That is, in the automatic adjustment of the tabletop 14A of the examination table 14 based on the camera image, it is desired that the tabletop 14A of the examination table 14 is moved to a position where the parietal part Par of the examinee is irradiated with the light localizer.

FIG. 26 is a schematic diagram illustrating a problem in scanogram imaging start position detection in a case of measuring the head. FIG. 27 is a partially enlarged view of FIG. 26. FIGS. 26 and 27 schematically show a state in which the examinee placed on the tabletop 14A of the examination table 14 is imaged using the camera 27.

In a case in which a measurement target part is the head, the scanogram imaging start position is set not directly below or close to directly below the camera 27, but at a position away from directly below the camera 27 in the front-rear direction. In a case of being viewed from the camera 27, the head of the examinee is in a position looking diagonally down, and the scanogram imaging start position line SSL in the camera image appears to be located at the position of the parietal part Par.

On the other hand, the movement amount of the tabletop 14A is calculated with a pixel position on the tabletop 14A in the camera image as a target. That is, a position Pb on the tabletop 14A in the camera image is used for calculating the movement amount of the tabletop 14A.

Then, in a case in which the tabletop 14A is actually moved and irradiated with the light localizer based on the calculation result of the movement amount of the tabletop 14A, the light localizer is emitted at the position Pb or in the vicinity of the position Pb.

Although the calculation of the movement amount of the tabletop 14A for moving the tabletop 14A to the position Pb is correctly performed, the position Pb deviates from the scanogram imaging start position line SSL on the camera image.

Therefore, the movement amount of the tabletop 14A based on the camera image is calculated in consideration of a distance La in the front-rear direction from a position Paa on the tabletop 14A, which is directly below the scanogram imaging start position line SSL in the camera image, to the position Pb on the tabletop 14A, as shown in FIG. 27.

FIG. 28 is a schematic diagram illustrating a problem in scanogram imaging start position detection in a case in which an abdomen is measured. The abdomen of the examinee has a shallower angle of view from the camera 27 than the head of the examinee, and a distance in the front-rear direction between a position Pc on the tabletop 14A and a position Pd of the abdomen of the examinee is smaller than the distance La in the front-rear direction between the position Paa directly below the position Pa of the parietal part Par and the position Pb on the tabletop 14A. Then, the tabletop 14A appears to be moved to a position approximately as expected, but the calculation of the movement amount of the tabletop 14A needs to be improved. Measurement of a chest is also the same as the measurement of the abdomen.

FIG. 29 is an explanatory diagram of the scanogram imaging start position detection in a case in which the head is measured. The scanogram imaging start position is based on the center position of the camera image. The center position of the camera image is an intersection of the lateral guide XG and the front-rear guide YG shown in FIG. 16 and the like.

A line segment LS1 directly downward from the camera 27 shown in FIG. 29 is a virtual line segment representing the center position of the camera image. That is, a position on the line segment LS1 represents the center position of the camera image for each height of the tabletop 14A.

In addition, a line segment LS2 diagonally downward from the camera 27 is a virtual line segment connecting pixels that always appear at the same position in the camera image. That is, a position on the line segment LS2 appears at the same position in the camera image for each height of the tabletop 14A. For example, the number of pixels PN1 from the center position of the camera image in the front-rear direction of a position Pe on the line segment LS2 is the same as the number of pixels PN2 from the center position of the camera image in the front-rear direction of a position Pf.

Therefore, in a case of calculating the movement amount of the tabletop 14A, the length-pixel conversion value at the height of the tabletop 14A at the position Pe is used instead of the length-pixel conversion value at the height of the tabletop 14A at the position Pf Specifically, the present invention can respond to the calculation by changing a calculation equation applied to the calculation of the movement amount in the front-rear direction.

FIG. 30 is a schematic diagram of the scanogram imaging start position detection in a case in which the head is measured. In the calculation of the movement amount of the tabletop 14A in the front-rear direction, an estimated value H__patient of the distance from the camera 27 to a surface SS of the examinee is used instead of the estimated value H__estimate of the distance from the camera 27 to the tabletop 14A.

The surface SS of the examinee described in the embodiment is an example of a surface of the measurement target part of the examinee that faces the sensor. The estimated value H__patient of the distance from the camera 27 to the surface SS of the examinee described in the embodiment is an example of sensor-to-measurement target part distance information.

FIG. 31 is an explanatory diagram of a mathematical equation used for the scanogram imaging start position detection. First, a length-pixel conversion value EstimateTableMppP at the height of the surface SS of the examinee where the scan start position is estimated is calculated. A calculation equation of the length-pixel conversion value EstimateTableMppP is shown as Equation 7 in FIG. 31.

The length-pixel conversion value EstimateTableMppP at the height of the surface SS of the examinee described in the embodiment is an example of first conversion information for converting the number of pixels in the camera image from the center position of the camera image to the measurement start position of the examinee into the distance from the center position of the camera image to the measurement start position.

Next, the number of pixels from the center position of the camera image to the scan start position is converted into a distance (middle_line_mm,middle_line_st_mm) in a unit such as millimeters, by using the length-pixel conversion value EstimateTableMppP. FIG. 31 shows a calculation equation of the distance middle_line_mm from the center position of the camera image in the lateral direction to the scan start position as Equation 8. In addition, FIG. 31 shows a calculation equation of the distance middle_line_st_mm from the center position of the camera image in the front-rear direction to the scan start position as Equation 9.

Based on Equation 9 in FIG. 31, a distance from the center position of the camera image in the front-rear direction to the scan start position at the height of the surface SS of the examinee is calculated. In addition, based on Equation 8 in FIG. 31, a distance from the center position of the camera image in the lateral direction to the scan start position at the height of the surface SS of the examinee is calculated.

Further, FIG. 31 shows a calculation equation of the distance high_table_middle_line_mm from the center position of the camera image in the lateral direction at the highest position to the scan start position as Equation 10. Further, FIG. 31 shows a calculation equation of the distance high_table_middle_line_st_mm from the center position of the camera image in the front-rear direction to the scan start position with respect to the highest position, as Equation 11.

The estimated value H__patient of the distance from the camera 27 to the surface SS of the examinee shown in FIG. 30 is also applied to calibration in a case in which the camera 27 is installed in a state of being inclined with respect to the installation surface PP.

That is, in a case in which the camera 27 is inclined with respect to the installation surface PP, the estimated value H__estimate of the distance from the camera 27 to the tabletop 14A is replaced with the estimated value H__patient of the distance from the camera 27 to the surface SS of the examinee.

In addition, the coordinate value Y_estimate in the front-rear direction of the estimated position, which is obtained by estimating the distance from the camera 27 to the surface SS of the examinee, is replaced with (Middle_line_st)−PNY, which is a value obtained by subtracting half of the number of pixels in the front-rear direction in the camera image from the coordinate value of the scan start position.

For example, the estimated value H__patient of the distance from the camera 27 to the surface SS of the examinee, which is estimated in a case in which the camera 27 is inclined with respect to the installation surface PP, is applied to Equation 7 shown in FIG. 31.

The length-pixel conversion value EstimateTableMppP calculated by using the estimated value H__patient of the distance from the camera 27 to the surface SS of the examinee, to which Equation 7 is applied, is applied to Equation 8, and the distance middle_line_mm from the center position of the camera image in the lateral direction to the scan start position is calculated.

In addition, the length-pixel conversion value EstimateTableMppP is applied to Equation 9, and the distance middle_line_st_mm from the center position of the camera image in the front-rear direction to the scan start position is calculated.

Further, with respect to the highest position of the tabletop 14A, a distance high_table_middle_line_mm from the center position of the camera image in the lateral direction to the scan start position is calculated based on Equation 10. Further, with respect to the highest position of the tabletop 14A, a distance high_table_middle_line_st_mm from the center position of the camera image in the front-rear direction to the scan start position is calculated based on Equation 11.

Further, the moving distance move_shift_mm of the tabletop 14A in the lateral direction and the moving distance move_position_mm of the tabletop 14A in the front-rear direction are calculated. A linear function z=a₂×x+b₂ represented using the slope a₂ and the intercept b₂ shown in Equation 7 is an example of a linear function representing the conversion relationship between the number of pixels of the camera image and the distance for each position in the up-down direction.

Effects of Other Embodiments

With the examination control device 20 according to another embodiment, the estimated value of the distance from the camera 27 to the surface SS of the examinee in a case in which the camera 27 is inclined with respect to the installation surface PP is converted into the estimated value H__patient of the distance from the camera 27 to the surface SS of the examinee at the center position of the camera image in a case in which the camera 27 is not inclined with respect to the installation surface PP. As a result, the moving distance to the scan start position in a case in which the camera 27 is inclined with respect to the installation surface PP is calculated by using the calculation method of the moving distance to the scan start position, which is applied in a case in which the camera 27 is not inclined with respect to the installation surface PP.

In another embodiment, the calculation of the moving distance to the scan start position of the tabletop 14A in the measurement of the head is illustrated, but the measurement target part is not limited to the head, and the calculation of the moving distance to the scan start position of the tabletop 14A according to another embodiment can be applied to the measurement of the chest, the abdomen, the waist, and the leg.

The examination control device 20 shown in FIG. 2 calculates the movement amount of the tabletop 14A described as another embodiment. That is, the examination control device 20 functions as an examination table movement control device that controls the movement of the examination table 14 and the tabletop 14A, and functions as a main body of the examination table movement control method.

Regarding Program for Operating Computer

A program causing a computer to implement some or all of the processing functions of the examination control device 20 and the like according to the embodiment can be recorded in a computer-readable medium which is an optical disk, a magnetic disk, a semiconductor memory, or other tangible non-transitory information storage medium, and the program can be provided via the information storage medium.

Instead of the aspect of providing the program by storing the program in the tangible non-transitory computer-readable medium, it is also possible to provide the program as a program signal by using an electric communication line such as the Internet.

Further, some or all of the processing functions in the examination control device 20 or the like may be implemented by cloud computing, or may be provided as software as a service (SaaS).

Example of Application to Medical Image Diagnostic Examination System

The measurement device 12 and the examination control device 20 shown in FIG. 1 may be electrically connected to each other via any network in a data communicable manner to constitute a medical image diagnostic examination system. The data communication between the measurement device 12 and the examination control device 20 may be wired communication or wireless communication.

The present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the technical idea of the present disclosure.

EXPLANATION OF REFERENCES

• • 10: MRI apparatus
  • 12: measurement device
  • 14: examination table
  • 14A: tabletop
  • 17A: imaging room
  • 20: examination control device
  • 27: camera
  • 82: processor
  • 84: memory
  • 126: calibration data generation unit
  • 130: camera image acquisition unit
  • 132: camera image processing unit
  • 134: distance information acquisition unit
  • 136: distance information processing unit
  • 138: actual measurement data acquisition unit
  • 140: actual measurement data processing unit